<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .box {
            margin: 50px auto;
            width: 600px;
            height: 200px;
            line-height: 200px;
            text-align: center;
            font-size: 60px;
            font-weight: 900;
            background-size: 1800px 200px;
            background: linear-gradient(45deg, #4cd137, #3498db, #4cd137, #3498db, #4cd137, #3498db) 0 0;
            -webkit-background-clip: text;
            color: transparent;
            text-shadow: 2px 3px 5px rgba(100, 100, 100, .3);
            transition: 2s;
            animation-name: trans;
            animation-iteration-count: infinite;
            animation-timing-function: linear;
            animation-duration: 5s;
        }

        @keyframes trans {
            0% {
                background-position: 0 0;
            }
            100% {
                background-position: 1200px 0;
            }
        }
    </style>
</head>
<body>
<div class="box">Look at me!</div>
</body>
</html>